2) Many populations exhibit the logistic growth curve a) Describe what is occurring during each phase of the curve. b) Discuss THREE factors that might cause fluctuations in the curve c) Organisms demonstrate exponential (r) or logistic growth (K) reproductive strategies. Explain these two strategies and discuss how they affect population size over time.

3) Living organisms play an important role in the recycling of many elements within an ecosystem. Discuss how various types of organisms and their geochemical reactions contribute to the recycling of either the carbon or the nitrogen in an ecosystem. Include in your answer one way in which human activity has an important impact on the nutrient cycle you have chosen.

4) Describe and give an example of each of the following. Include in your discussion the selective advantage of each: a. Pheromones b. Mimicry c. Stereotyped